This invention relates generally to the displacement of a mobile robot and is particularly directed to a navigation system and method to permit a mobile robot to detect, navigate to, and be recharged by a charging unit following detection of a low charge state in its storage battery.
The impact of robotics in areas ranging from the work place to the home is rapidly increasing. Industrial applications typically involve the high speed, repetitive performance of a specific task by a movable arm having grasping means on one end and which is generally capable of multi-axis movement. Mobile robots are similarly being used in increasing numbers of applications where it is necessary to transport an object between designated locations or to perform a given task at more than one location. In the home, mobile robotic systems are becoming increasingly popular with hobbyists as well as in toys and in electro-mechanical apparatus of an instructional nature.
Two primary considerations with regard to mobile robots relate to the manner in which the robot is powered, or energized, and to its navigation system. Some mobile robots are controlled and powered by means of an electrical cable coupled to the robot which, while simplifying the navigation system required and the number of instructions which the robot is requird to "learn", limits the mobility of the robot and thus the range of tasks which it may perform. In battery powered robots the requirement for an attached power cable is eliminated and displacement of the robot typically involves the positioning of numerous sensors/emitters in the immediate vicinity of the robot or a "track" system which the robot follows in moving from place to place.
Where the mobile robot is powered by a rechargeable battery, the prior art has made use of elongated strips positioned upon the floor which the robot senses and follows in the direction of a recharging unit upon detection of a low charge condition. When the robot arrives at the recharging unit, a plug and socket arrangement is generally provided to allow the robot to mate with the charger for recharging its storage battery or batteries. In addition to the undesirable feature of requiring numerous guide strips positioned upon the surface on which the robot moves, such systems suffer from another limitation in that if the robot makes an incorrect turn while on or upon reaching the guide strip system, the robot may travel away from rather than toward the recharging unit. If this error is not detected quickly enough, the robot may become fully discharged before it arrives at the recharging unit.
The present invention represents an improvement over the prior art in that by making use of a unique navigation system and method for a mobile robot it does not suffer from the aforementioned limitations. A combined opto/acoustic navigation system permits the robot to detect a charging unit in the room within which it is positioned. The navigation system then allows the robot to detect and navigate about obstacles while traveling to a position directly in front of the charging unit to permit the robot to dock with the floating plug-equipped charging unit for the recharging of its storage battery.